Abstract: Thirty two flavonoid compounds were screened for inhibition of rat lens aldose reductase activity, among which baiclein and lsohyperoside acetate were found to exhibit markedly enzyme-inhibitary activities with IC₅₀ values of 3.5×10^-6 M and 2.2×10^-6 M, respectively. Baiclein displayed a mixed noncompetitive and competitive inhibition, while isohyperoside acetate a mixed noncompetitive and uncompetitive type of inhibition.Increased aldose reductase activity has been implicated in pathogenesis of diabetic complications so that treatment of these diabetic complications with aldose reductase inhibitors may be a valid approach.